Leslie described 2 studies answering the question of the changes of orthognathic surgery, first on the airway, second in the stability of a 3 part maxilla using CBCTs.
- Airway changes investigated with CBCT on 36 orthognathic patients
Significant changes (mainly oropharyx) in volume were:
- Maxillary advance: 76% increase
- Mandibular advance: 49% increase
- Bimaxillary procedure: 143% increase
What variables resulted in the increase in volume?
- Bimaxillary procedure
- Every 1mm of advancement of greater palatine foreman = 2000mm3
- Every 1mm downwards movement of PNS = 1000 mm3
What didn’t change?
- No significant change on nasopharynx
- Stability of 3 part maxillary orthognathic surgery and BSSO advancement investigated with CBCT for 29 orthognathic patients.
Study follow up 18 months with repeat CBCT
- 3 part maxilla surgery changes:
- Posterior maxilla relapsed superiorly 1.5-2mm
- Advancement relapse 5mm
- No expansion relapse
- BSSO advancement changes:
- Mental foreman relapse 2.5mm
- Interlingula distance decrease 2.8mm
- Immediate post operatively condyles move posteriorly 0.6-1.4mm and medially 1.2mm
- 18 months post operatively condyle returns pre-operative position
- Bimaxillary advancement: relapse 18%